12021821 has 8 divisors (see below), whose sum is σ = 13761024. Its totient is φ = 10288080.

The previous prime is 12021817. The next prime is 12021857. The reversal of 12021821 is 12812021.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 12021821 - 2² = 12021817 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 12021821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12021871) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6071 + ... + 7803.

It is an arithmetic number, because the mean of its divisors is an integer number (1720128).

Almost surely, 2^12021821 is an apocalyptic number.

It is an amenable number.

12021821 is a deficient number, since it is larger than the sum of its proper divisors (1739203).

12021821 is an equidigital number, since it uses as much as digits as its factorization.

12021821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2731.

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 12021821 is about 3467.2497746773. The cubic root of 12021821 is about 229.0815356448.

Adding to 12021821 its reverse (12812021), we get a palindrome (24833842).

The spelling of 12021821 in words is "twelve million, twenty-one thousand, eight hundred twenty-one".